The objective of the present research proposal is to determine the chemical nature of the DNA-protein cross-linking formed in mammalian chromatin when it is irradiated with nucleic acid bases and amino acids are involved in forming the cross-links? What are the chemical structures of those adducts that are important in forming DNA-protein cross-links? The experiments planned will emphasize the nature of the cross-links formed between DNA and chromosomal proteins in general and between DNA and histones in particular.